Periodic Motions

"The task is done; the Maker rests. And lo! The engine turns. A million years shall flow, Ere round its axle shall the wheel run slow And a new cog be needed .... " Mad8.ch: The Tragedy of Man J.C.W. Horne's translation In this book I tried to sum up the facts and results I considered most important concerning periodic solutions of ordinary differential equations (ODEs) produced by this century from Henri Poincare up to the youngest mathematician appearing in the list of references. I have inclu